Contrast Induced Nephropathy Evaluation using Multiple immunoAssays

Iodinated contrast media (ICM) are administered intravenously in a large part
of Computer Tomography (CT) scans to enhance differences between normal and
pathologic structures. The ICM are diagnostic drugs which can cause
nephropathy. The incidence of this contrast induced nephropathy (CIN) in high
risk patients reported thus far in scientific papers is up to 50 percent. In
the general population the incidence reported is 3 to 4 percent. Contrast
induced nephropathy accounts for up to 12 percent of all cases of hospital
acquired acute renal failure. Acute renal failure is associated with a high
mortality rate, a prolonged hospitalization and an impaired drug excretion.

In many hospitals a protocol on contrast media safety is issued to identify
high risk patients. Preventive measures are taken in high risk patients. These
include hydration and stopping nephrotoxic medication if possible. The
incidence in non-hospitalized patients despite preventive measures is not well
known. This study will estimate the incidence of CIN in this population.

The definition of CIN is an increase of serum creatinine of at least 44
micromole/l or a relative increase of at least 25% from baseline within 3 days
after intravenous contrast administration without another aetiology to explain
the increase.

Renal function is best estimated by the glomerular filtration rate (GFR). The
GFR can not be measured directly. It is estimated using the 4-point Modified
Diet in Renal Disease (MDRD) formula, which take ages, sex, ethnicity and serum
creatinine into account. Serum creatinine is subject to variation in production
and secretion, thus making GFR estimation inaccurate. In this study the
possible correlation between CIN, microalbuminuria and microglobulinuria will
be evaluated.

Adding more sensitive biomarkers microalbuminuria and microglobulinuria to
serum creatinine can provide information on the exact mechanism of renal damage
and the identification of high risk patients.

The aim of the current study is to:
1. Determine the incidence of CIN after introduction of preventive measures.
2. Describe changes in the course of biomarkers serum creatinine, microalbumin
and microglobulin related to intravenous ICM administration.
3. Compare microalbumin and microglobulin values between the identified high
risk and non-high risk group before ICM administration.
4. Describe the possible correlation between the amount of ICM administered
intravenously and the incidence of renal damage and CIN.

This is a single-centre, prospective, observational study.

Patients will be asked for a blood and urine sample before and between day 2
and 4 after administration of iodinated contrast media. The blood sample
consist of one venous punction. The patient will be asked to collect a first
morning urine sample.
This sampling is associated with a minimal patient risk and burden.

The patient group will benefit from the results of this study because of the
better understanding of the mechanism of CIN. The individual patient could
benefit in terms of early discovery of renal dysfunction. If renal dysfunction
is established, the patient will be consulted by a nephrologist.